This invention relates to switched capacitor circuits or networks for simulating electrical impedance elements, and more particularly to a switched capacitor circuit replacement for an inductor and/or the parallel combination of an inductor and a capacitor.
A switched capacitor floating-inductor simulation circuit that is relatively insensitive to parasitic capacitance is described in the article "Switched Capacitor Filters Using Floating-Inductance Simulation Circuits" by Man Shek Lee, Electronics Letters, Sept. 27, 1979, Vol. 15, No. 20, pages 644-645, and in the U.S. patent application "Switched-Capacitor Floating-Inductor Simulation Circuit" by Man Shek Lee, Ser. No. 162,981, Filed June 25, 1980, U.S. Pat. No. 4,333,157, Issued Jun. 1, 1982, both of which are incorporated herein by reference. The inductor simulation circuit described there requires matched capacitors, however, to simulate a truly floating lossless inductor or impedance. It is desirable to have switched capacitor types of simulation circuits that do not depend on the matching of components. An object of this invention is the provision of a switched capacitor circuit that does not require matching of components to simulate a desired impedance. Another object is the provision of a switched capacitor circuit that simulates an inductor. A further object is the provision of such a circuit that simulates the parallel combination of an inductor and a capacitor.